Direct experimental observation of total absorption and loss compensation using sound waves with complex frequencies
Abstract
In this study, we experimentally investigate the application of a transient signal with complex frequencies to the absorption and transmission of sound waves. Indeed, the emission of a wave with an exponentially varying amplitude in time is analogous, in the frequency domain, to a monochromatic wave with spatial gain or loss. Our results show that by exciting a non-critically coupled Helmholtz resonator with a wave having a growing amplitude, total absorption can still be achieved. Furthermore, the lossy propagation of a traveling wave in a duct is also studied, and it is shown that the losses embedded in the complex wavenumber can be compensated by using a transient signal with decreasing amplitude. These results confirm the potential of complex frequency excitation for exploring new means of manipulating sound waves to mimic gain and loss.
Keywords
Cite
@article{arxiv.2503.11748,
title = {Direct experimental observation of total absorption and loss compensation using sound waves with complex frequencies},
author = {Anis Maddi and Gaelle Poignand and Vassos Achilleos and Vincent Pagneux and Guillaume Penelet},
journal= {arXiv preprint arXiv:2503.11748},
year = {2025}
}